1. Field of the Invention
This invention relates to a device for rapid orthodontic tooth movement into a fresh tooth extraction space for correcting severe front teeth crowding or protrusion in orthodontic treatment.
2. Description of the Prior Art
Conventional orthodontic treatment for severe anterior teeth crowding or protrusion generally takes one and half to two years. Generally, there are five steps in the treatment procedure.
1. Extracting the first premolars. PA1 2. Initial teeth leveling by using orthodontic brackets and arch wires. Depending on the alignment of teeth, this step lasts about three to six months. PA1 3. Retracting canine backward into the first premolar extraction space for anterior teeth. This step lasts about four to six months for children and seven to eight months for adults. PA1 4. Retracting anterior teeth to level the protruding teeth. This step lasts about six months. PA1 5. Fine adjustment of occlusion and tooth angulation. This step lasts about three to six months.
This treatment procedure is too long to the patients. It is not esthetic to wear braces for such a long period and it is very burdensome for the patients to maintain their oral hygiene as well. It also is very inconvenient and time-consuming for the patients to visit orthodontist's office in such a long period. Two major steps make the period of orthodontic treatment long. They are the step 3 (canine retraction) and step 4 (anterior retraction), which take a whole year in a total. Several efforts including using postaglanding injections into the periodontal ligaments have been made to shorten the time needed for these two steps. However, the results are not very convincing in the clinical point of view and it is very painful for the patients as well.
FIGS. 1 and 2 show the conventional method for canine retraction after first premolar extraction with an elastic power chain. The first molar 1 is engaged with a molar band 12 and a bracket 121 welded on the buccal surface thereof. The canine 3 is engaged with a canine band 32 and a bracket 321 welded on the buccal surface thereof. An elastic power chain 2 is engaged between the brackets 121 and 321. Through the elastic force of the elastic power chain 2, the canine 3 can be pulled gradually toward the first molar 2 and a space is left behind the canine. The regular rate of canine retraction with elastics is 1 mm per month. It takes 4-6 months to retract a canine into a desirable position accordingly. After the canine had been retracted all the way back into the first premolar space, the anterior teeth have gotten space for anterior retraction.
The strength of the elastic power chain 2 is not consistent to control the tooth movement. It absorbs saliva and deteriorates quickly in patient's mouth. It has to be changed frequently, which causes a lot of inconvenience for the patients as well. For people with a busy life and working schedule, this is simply just too long and not good enough.